KR100425575B1 - Magnetic recording device, method of adjusting magnetic head and magnetic recording medium - Google Patents

Abstract

Provided is a fixed magnetic recording apparatus capable of controlling an imbalance in manufacturing a longitudinal bias magnetic field of a hard bias magnetic head and an effective track width. In the magnetic recording apparatus comprising a hard bias type magnetic head in which a hard magnetic film 3 for adding a magnetic field in the longitudinal bias direction to the magnetoresistive film 1 and performing magnetic block control is provided, the hard magnetic film 3 ), A solenoid (4) for adjusting the magnetic field in the longitudinal bias direction is installed. As a result, the magnetic field in the longitudinal bias direction can be finely adjusted and maintained at an optimum value, whereby the linear responsiveness of the reproduction output of the magnetic head can be improved, and the effective track width of the magnetic head can be adjusted.

Description

Magnetic recording device, magnetic head control method, and magnetic recording medium {MAGNETIC RECORDING DEVICE, METHOD OF ADJUSTING MAGNETIC HEAD AND MAGNETIC RECORDING MEDIUM}

In recent years, in the fixed magnetic recording apparatus, the speed of reading / writing characteristics has been demanded in accordance with the demand for increasing recording density every year, and the reproduction system has also been required to have higher sensitivity to magnetic flux than in the prior art. Currently, a magnetoresistive head (MR head) in which a reproducing output does not depend on the circumferential speed of a magnetic recording medium, that is, a head of a reproducing method using a magnetoresistive effect whose magnetic resistance changes by an external magnetic field is employed. There are many cases. In addition, it is considered that a part of the sensor for detecting the magnetic flux is now formed into a multilayer film, which has been shifted to a GMR head having improved reproduction efficiency.

As a practical GMR head, there is a spin valve film head using a spin valve film in a multilayer film as a magnetic sensing unit. The GMR / induction hybrid head is configured to record data using a conventional thin film (MR film) head, and to read data by a GMR head disposed adjacent to the thin film head. In short, the GMR head is used exclusively for reading, but the reproducing output obtained is significantly larger than the thin film head, the reproducing output does not depend on the circumferential speed of the magnetic disk, and the track width read from the thin film head for recording is made small. This allows the influence of adjacent tracks at the time of reading to be reduced. For this reason, it is widely used as a head for HDD. However, since the operation principle of the GMR head requires a bias current, it is necessary to prevent distortion of the reproduction signal waveform by optimally controlling the bias current.

By the way, when the GMR head which uses a multilayer film for magnetic sensing parts, such as the said spin valve film head, is utilized, the biggest challenge is to reliably single-magnetically partition NiNi which is a free side magnetic film. If the free side magnetic film is not single magnetically partitioned, a waveform variation called Barkhausen noise occurs due to a magnetic field from the outside, and signal noise is generated. By magnetically partitioning the free side magnetic film, Barkhausen noise is eliminated and a good reproduction output is obtained. As a method of monomagnetic partitioning a magnetic film, there is a method of arranging a magnetic block control film at the end of the magnetic film. As the magnetic block control film, in addition to using the exchange coupling of the antiferromagnetic film, a single magnetic segmentation can be achieved by using a magnetic field (hard bias method) of a permanent magnet. Therefore, the material and configuration of this magnetic compartment control film are important and considered the most important in developing the spin valve film head.

However, in the construction of a hard biased head, in the present situation in which the track pitch is getting smaller every year, the generation of magnets is more precise, and thus the imbalance between the rods due to difficulty in controlling the process cannot be ignored. do. If the magnet is too strong, the GMR around the magnet disappears. Nevertheless, once the permanent magnet is incorporated in the thin film forming process, it is not easy to correct it. Therefore, at the time of shipment inspection, the track center of the actual playhead is greatly displaced from the design center, and it is discarded as a defective part. This is the current situation. Therefore, the development of the technology which can fine-tune track width becomes a subject.

Disclosure of Invention The present invention solves the above problem, and in the magnetic bias of the hard bias type system, a good reproduction output can be obtained and the track width can be finely adjusted when the actual track width is out of the design value. It is to be done.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stationary magnetic recording apparatus in an electronic device, a method of adjusting a magnetic head, and a magnetic recording medium.

1 is a schematic overall structural diagram of a magnetic recording apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a structural diagram of a reproduction head of the magnetic recording apparatus shown in FIG.

3 is an explanatory diagram of a wiring pattern as current control means of the magnetic recording apparatus shown in FIG.

FIG. 4 is a characteristic diagram showing the magnetization response curve when the longitudinal bias curve is changed in the reproduction head of FIG. 2.

5 is a structural diagram of a reproduction head constituting a magnetic recording apparatus according to the second embodiment of the present invention.

Fig. 6 is a flowchart for explaining the change in the effective track width of the magnetic recording apparatus in the third embodiment of the present invention.

7 is a waveform diagram in which the playhead reads the servo information.

8 is a reproduction output characteristic diagram when the reproduction head is shifted in the TPI direction.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, in the magnetic head provided with the multilayer film which has arrange | positioned the hard magnetic film (hard bias film) for adding a longitudinal-biased magnetic field to a magnetoresistive film, a solenoid is added to a hard bias film. The magnetic field in the longitudinal bias direction is controlled by the current flowing through the solenoid.

In this way, even if some imbalance occurs in the hard bias film in the process of the head process, the strength of the hard bias film can be changed by adjusting the amount of current flowing through the solenoid, and the effective track width can be made variable. This makes it possible to operate the regeneration head at the point of the magnetization curve having the best regeneration output, or to adjust the effective track width even after the reproducing head is manufactured, to improve imbalance in manufacturing the head and to improve the product yield. In addition, the reliability of the driver can be improved. In addition, the linear response can be improved.

The magnetic recording apparatus of the present invention is a magnetic recording apparatus having a hard bias type magnetic head in which a hard bias film for adding a magnetic field in the longitudinal bias direction to a magnetoresistive film and for performing magnetic block control is provided. It is characterized in that the solenoid is installed to adjust the magnetic field in the longitudinal bias direction. This configuration makes it possible to maintain the magnetic field in the longitudinal bias direction at an optimum value, thereby improving the linear responsiveness of the regeneration output of the magnetic head, and to operate the magnetic head at the point of the magnetization curve having the best regeneration output. Can be. Therefore, even when there is an error in dimensions or an imbalance in the strength of the magnet in the hard bias film formed in the head fabrication process, the magnetic head can be brought to a stable operating point. In addition, the effective track width of the magnetic head can be adjusted, and the effective track width can be corrected in response to the influence of dimensional imbalance at the time of manufacture, skew angle, head float rate, and the like.

In addition, a current generation circuit for generating a longitudinal bias current supplied to the solenoid is provided in the vicinity of the magnetic head, whereby noise in the reproduction output can be prevented.

In addition, a current control means for controlling the longitudinal bias current supplied to the solenoid is provided as a wiring pattern and placed on the suspension of the magnetic head, so that the longitudinal bias control line can be added.

In addition, the current control means for controlling the longitudinal bias current supplied to the solenoid includes a measurement unit for measuring the effective track width of the magnetic head, a difference between the measured value measured at the measurement unit and the design value, and based on the calculation result. And a current controller for determining a value, and a current controller for controlling a current supplied to the solenoid so as to be a current value determined by the calculator.

The adjustment method of the magnetic head of the present invention is a hard bias type magnetic head adjusting method in which a hard bias film for adding a magnetic field in the longitudinal bias direction to a magnetoresistive film and performing magnetic block control is provided. It is characterized by controlling the current supplied to the solenoid and improving the linear responsiveness of the regenerative output of the magnetic head by the magnetic field generated in the solenoid. This configuration makes it possible to operate the magnetic head at the point of the magnetization curve whose reproduction output is best.

Further, by controlling the current supplied to the solenoid provided in the hard bias film, the magnetic field generated in the solenoid increases and decreases the regeneration inactive region of the magnetic head and changes the effective track width. This configuration can offset the unbalance of the effective track width due to the dimensional imbalance at the time of manufacture, the influence of the skew value, the head float rate, etc., and can eliminate the defect of the head due to the deviation of the effective track width. . It is also possible to make the effective track width constant.

In addition, the effective track width of the magnetic head is measured by the measuring means, the current value supplied to the solenoid based on the measured value and the design value is determined by the calculation determining means, and by the current adjusting means to make the determined current value. It is characterized by controlling the current.

In the magnetic recording medium of the present invention, the effective track width of the magnetic head is measured by the measuring means, and based on the measured value and the design value, the current value supplied to the solenoid is determined by the calculation determining means, and the determined current value is determined. And an execution means for executing a series of operations for controlling the current by the current adjustment means. With this arrangement, when the magnetic head is moved to a desired track of the magnetic recording medium, the execution means is read out to perform the above series of operations, and the effective track width of the magnetic head is adjusted.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described concretely, referring drawings.

Embodiment 1

Fig. 1 shows a schematic structure of a magnetic recording apparatus according to Embodiment 1 of the present invention, and Fig. 2 shows a structure of a magnetic sensing unit of a magnetic head (hereinafter referred to as a reproduction head) of the magnetic recording apparatus. In Fig. 1, A is a magnetic recording medium, B is a reproduction head, and C is a suspension for supporting the reproduction head B to the apparatus body. In Fig. 2, 1 is a magnetoresistive film (MR film or spin valve film) which detects a change in the magnetic field from the magnetic recording medium and obtains a reproducing output, and 2 is an electrode which transmits a signal of the magnetoresistive film 1; , 3 is a hard magnetic film provided at both ends in the longitudinal direction of the magnetoresistive film 1 to apply a magnetic field to the magnetoresistive film 1 in the longitudinal direction and to suppress Barkhausen noise. Materials such as NiFe-based materials are used for the magnetoresistive film 1, and materials such as CoCrPt-based materials are often used for the hard magnetic film 3.

Reference numeral 4 is a solenoid which is provided to surround the hard magnetic film 3 in the vicinity of the magnetoresistive film 1 and adjusts a magnetic field generated by the hard magnetic film 3 by a current flowing therein, and 5 is a solenoid. As a current generation circuit for generating a current flowing in (4), it is provided inside the preamplifier 6 (may be near). 7 is a wiring pattern for controlling the current flowing from the current generation circuit 5 to the solenoid 4, and is shown in FIG. 3 on the FPC (flexible wiring board) 8 mounted on the suspension C such as a leaf spring. It is laid as follows.

In such a magnetic recording apparatus, when the longitudinal bias magnetization ratio of the reproduction head B changes, the magnetic field response curve is shifted. The longitudinal bias magnetization ratio is an index indicating the degree of thickness of the magnetic block control film, and the saturation magnetic flux density (Bs3) and the film thickness (t3) of the hard magnetic film 3 are determined by the saturation magnetic flux density of the MR film 1 ( It is the value divided by Bs1) and the film thickness (t1). Therefore, it can be said that the hard magnetic film 3 that is the magnetic compartment control film is stronger as the longitudinal bias magnetization ratio is larger.

4 shows magnetic field response curves at various longitudinal bias magnetization ratios. The vertical axis represents the output voltage and the horizontal axis represents the magnetic field applied from the outside. As shown in Figs. 4A and 4B, when the longitudinal bias magnetization ratios are as small as 0.7 and 1.0, it can be seen that strange portions appear in the hysteresis of the loop and that Bachhausen noise is generated. On the other hand, as shown in Figs. 4 (c) and 4 (d), when the longitudinal bias magnetization ratios are as large as 1.4 and 1.7, the Barkhausen noise is improved to be invisible. In such a case, the magnetoresistive film 1 is considered to be self-organizing.

However, as the longitudinal bias magnetization ratio increases, the slope of the inclined portion of the magnetic field response curve becomes slower. If the longitudinal bias magnetization ratio is too large, the sensitivity of the device becomes worse, the reproduction waveform becomes smaller and not sharp. This is because the movement of the magnetic body of the magnetoresistive film 1 is bound by the magnetic field in the TPI direction (radial direction of the recording medium) generated by the hard magnetic film 3 as the magnetic compartment control film.

For this reason, by flowing a current through the solenoid 4, a magnetic flux is generated in the longitudinal direction of the hard magnetic film 3, the longitudinal bias magnetic field is adjusted, and a good magnetic response without Barkhausen noise is obtained. By making the direction of the electric current which flows through the solenoid 4 into reversible, it is possible to make a longitudinal bias magnetic field larger or smaller.

Therefore, even when there is a dimension error in the hard magnetic film 3 formed in the head fabrication process or there is an imbalance in the magnetic strength, by adjusting the magnetic field in the longitudinal bias direction by the current flowing through the solenoid 4 This makes it possible to bring the playhead B to a stable operating point.

Embodiment 2

Fig. 5 shows the structure of the magnetic sensing unit of the reproduction head of the magnetic recording apparatus in Embodiment 2 of the present invention, which has the same configuration as the reproduction head of the magnetic recording apparatus described in Embodiment 1 above. The same code | symbol as FIG. 2 is attached | subjected to the member which has the same effect | action, and description is abbreviate | omitted. Members other than the playhead use FIGS. 1 and 3.

In addition, the wiring pattern 7 includes a measurement unit for measuring the effective track width (described later) of the reproduction head B, and calculates a difference between the measured value measured at the measurement unit and the design value, and calculates an optimum current value flowing through the solenoid. An arithmetic decision unit for determining and a current regulation unit for adjusting a current flowing through the solenoid to be a current value determined by the arithmetic decision unit.

As shown, the magnetoresistive film 1 in the vicinity of the hard magnetic film 3 is in fact not regenerated as a regeneration sensor due to the magnetic influence of the hard magnetic film 3 (in some cases, the spindle film). The effective track width is made narrower by the portion where the film inert region 9 does not play a role as a sensor.

For this reason, the following operations are appropriately performed by the wiring pattern 7 in order to bring the effective track width closer to the design value. That is, the effective track width of the playhead B is measured by the measuring unit, the difference between the measured value and the design value is calculated by the calculating unit, and the optimum current value is determined, and the current adjusting unit is set to the determined current value. Adjust the current by

In other words, when the effective track width is to be narrowed, a current flows to the solenoid 4 so that the regeneration film inactive region 9 is made large, and when the effective track width is made wide, the regeneration film inert region 9 is made small. The solenoid 4 is made to flow in the reverse direction to the above.

By doing in this way, the effective track width changed by the influence of the dimensional imbalance at the time of manufacture, the skew angle, the head float rate, etc. can be corrected so as to be close to the design value.

Embodiment 3

In order to bring the effective track width of the reproduction head of the magnetic recording apparatus as described in the second embodiment closer to the design value, the following operation is performed in the factory shipment process of the reproduction head. The code | symbol of each member, such as a playhead, conforms to Embodiment 2. As shown in FIG.

As shown in the flowchart of Fig. 6, in # 1, the target track width TWO, the solenoid current amount i, the off track amount d, the maximum off track number N, and the measurement track n are initialized. Set it.

In # 2, for each track of the magnetic recording medium A, A and B bursts previously recorded by the servo track writer are read by the reproduction head, and the magnitudes of the outputs of the A and B bursts are compared, and both Let the track output D0 be the point at which the outputs are the same. 7A and 7B show waveforms in which the playhead reads the servo information.

Next, in # 3, measurement data is recorded using the recording head at the position of the track center D0. In that case, a 2T pattern is used for the servo frequency. For example, in the case of a 60 MHz servo frequency, a 15 MHz repetition pattern is recorded.

In # 4, the off track value register is set to j = -N, the reproduction output is set to Ep = 0, and the off track value when the reproduction output is at a peak is set to jp = -N + 1. In # 5, the current direction of the solenoid current amount i is set.

Further, in # 6, the reproduction head B facing the magnetic recording medium A is offtracked by the distance d from the track center D0 in the TPI direction (radial direction of the recording medium) so that the position D = D1 (position of measurement data, i.e., displacement from track center D0) is positioned at + j × d, and at # 7, measurement data is input to track center at position D, so D1 = 0. .

Next, in # 8, the measured reproduction output E is compared with the reproduction output Ep = 0 which is a set value. If the measured value is larger than the set value, in # 9, the reproduction output E is stored as the set value Ep of the reproduction output, and the off track value jp at that time is set to the off track number. Remember as (j). If the measured value of the reproduction output is smaller than the set value, the initial set value is kept as it is.

Next, in # 10, the set value j is compared with the number of tracks N. If the set value j is smaller, the set value j is increased by 1 in # 11. , # 6 and later operations are performed.

If the set value j is larger, as shown in FIG. 8, the maximum reproduction output point EP at which the reproduction output E is peaked is detected as shown in FIG. ) Detects the off-track amount TW1 in the outer circumferential direction and the off-track amount TW2 in the inner circumferential direction, which results in a 50% reproducing output (EP / 2), and between the off-track amounts TW1 and TW2. The effective track width TW, which is defined as the distance of, is obtained.

Next, in # 13, it is determined whether the effective track width TW is the same as the track width TW0 which is preferable in design, and if it is not the same, the solenoid current amount i is changed in # 14. The operation after # 5 is performed. If the actual track width TW is found to be the same as the track width TWO desirable in design, the process ends.

In this way, the optimum amount of current flowing through the solenoid 4 can be obtained in correspondence with each track of the magnetic recording medium A. FIG.

In addition, the amount of current actually flowing to the solenoid 4 may be determined for each track of the magnetic recording medium A based on the amount of current obtained as described above, and is directed from the outer peripheral side of the magnetic recording medium A to the inner peripheral side. Alternatively, a track group consisting of a plurality of tracks arranged in sequence may be set and determined for each track group.

On the other hand, in the magnetic recording medium A, execution means for executing a flow for obtaining the current amount flowing in the solenoid 4 as described above, for example, execution means is read to move the program to each data area, and the solenoid 4 Current is adjusted so that the effective track width (TW) is close to the design value.

Claims (8)

A hard bias magnetic head (B) having a hard bias film (3) for adding a magnetic field in the longitudinal bias direction to the magnetoresistive film (1) and performing magnetic block control is provided, and the hard bias film (3) is provided. A magnetic recording device comprising a solenoid 4 for adjusting a magnetic field in the longitudinal bias direction, And current control means for controlling a longitudinal bias current supplied to the solenoid 4, wherein the current control means, A measuring unit that measures the effective track width TW of the magnetic head B, a calculation determining unit that calculates a difference between the measured value and the design value measured by the measuring unit, and determines a current value based on the calculation result, and a calculation determining unit And a current control unit for adjusting the current supplied to the solenoid (4) so as to be the current value determined in the above. A magnetic recording apparatus according to claim 1, wherein a current generation circuit (5) for generating a longitudinal bias current supplied to said solenoid (4) is provided in the vicinity of the magnetic head (B). 2. The magnet as claimed in claim 1, characterized in that the current control means for controlling the longitudinal bias current supplied to the solenoid 4 is a wiring pattern 7 provided on the suspension C of the magnetic head B. Logger. delete In the method of adjusting the magnetic bias B of the hard bias type in which a hard bias film 3 for adding a magnetic field in the longitudinal bias direction to the magnetoresistive film 1 and performing magnetic block control is disposed, As a method of controlling the current supplied to the solenoid 4 provided in the hard bias film 3 and improving the linear responsiveness of the regenerative output of the magnetic head B by the magnetic field generated in the solenoid 4, The effective track width TW of the magnetic head B is measured by the measuring means, and the current value supplied to the solenoid 4 is determined by the calculation determining means based on the measured value and the design value, and the determined current value Control method of the magnetic head, characterized in that for controlling the current by the current control means to be. In the method of adjusting the magnetic bias B of the hard bias type in which a hard bias film 3 for adding a magnetic field in the longitudinal bias direction to the magnetoresistive film 1 and performing magnetic block control is disposed, By controlling the current supplied to the solenoid 4 provided in the hard bias film 3, the magnetic field generated in the solenoid 4 increases and decreases the regeneration inactive region 9 of the magnetic head B, and the effective track width. As a method of changing the TW, the effective track width TW of the magnetic head B is measured by the measuring means, and arithmetic determination of the current value supplied to the solenoid 4 based on the measured value and the design value is performed. And the current is controlled by the current adjusting means so as to be determined by the means and to have a determined current value. delete The effective track width TW of the magnetic head B is measured by the measuring means, and the current value supplied to the solenoid 4 is determined by the calculation determining means based on the measured value and the design value, and the determined current value And a executing means for executing a series of operations consisting of controlling the current by the current adjusting means so as to be obtained.